Air-conditioner / Heat Pumps...

There is a lot more to heat pumps than many people realize and it can be hard to get good clean advice... we all want to promote certain brands, but hopefully we can offer a few pointers to look for no matter what brand you are considering.

General Information and Advice

If your question is not answered here please contact us for further information.

Are they really efficient?

Yes. No other electrical appliance comes anywhere near the operating efficiency of a quality heat pump. Most electrical appliances are 100% efficient - the electricity they use is the same as the heat they deliver. Inverter heat pumps can operate at efficiencies of more than 500% in some conditions.

Efficiency Example : A living room with a heat loading of 4.5 kw...

Standard 2 kw fan or oil heater

• Uses 2 kw of electricity to deliver 2 kw of heat - 100% efficiency
• The room is still short on its full comfort level by 2.5 kw per hour

Panasonic HE12GKE Heat Pump

• At 7°C outside it uses 1.04 kw to deliver 4.8 kw of heat - only half of what the fan heater used but it delivered the full heat loading.
• Even at -20°C the efficiency remains above 250%

But it gets better... once the heat pump has bought the room up to its heat loading the inverter technology begins to slow the machine down because its full performance is no longer needed to maintain the room temperature.

• The heat pump can operate down to 0.6 kw of heating using just 13 watts of electricity, if necessary.
• For a full days heating there is no competition - the heat pump wins easily

But they are not perfect!

• As the outside temperature drops the efficiency of the heat pump will also drop - but even at -10°C a good heat pump will still be doing way better than a standard fan heater! As a general rule - the cheaper a heat pump is the poorer its overall performance will be in terms of efficiency, heat output and cold rating.
• They are designed to heat single rooms / areas. They are not particularly good at heating multiple rooms though you may get good heat drift through double doors from a well positioned heat pump.
• Because they offer a high level of comfort, people tend to use them more than they would a fan heater that they know is expensive. Getting a lower power bill will not always be possible but you will be much warmer than you were before at a cost you can afford.
• They move air to provide heating and if not placed carefully they will cause breezes and drafts. Many people forget to use the auto-fan setting which ensures that the correct fan speed is always used according to the heat loading.
• They make noise. There is no such thing as a totally quiet heat pump. Be careful about reported quietness levels - the figure quoted is often the lowest manual fan setting where heating outputs are also very low.

How do you size a heat pump?

The heat loading is determined by the volume of air in your room and the estimated heat losses. The formula is... Width x Length x Height = cubic metres The intended area should be assessed by a qualified installer to establish the loading and to consult on the position of the indoor and outdoor units.

A room of 4m wide x 5m long x 2.4m high = 48m³. In general...

• Multiply a living area volume by 65 watts per cubic metre - 48 x 65 = 3,120 watts or 3.1 kilowatts
• Multiply a bedroom area* by 55 watts - 48 x 55 = 2,640 watts (2.6 kw)
• Multiply rooms in an older villa type building by 75 watts

* Unless the heat pump is wanted for a large bedroom with ensuite, don't measure all the bedrooms and think that you need a giant heat pump. A medium sized heat pump up to 6.0 kilowatts is a better solution for supplying a hallway and multiple bedrooms - large heat pumps do not work well in limited spaces -see a specialist for proper advice.

Does the outdoor unit have to go in a sunny, northern position?

No, but it is better. Good quality heat pumps operate down to -15°C to -20°C these days and their performance at H2 (0-2°C) is also improving. A particularly cold spot where frosty conditions are likely to prevail should still be avoided as this will increase the defrosting periods for any heat pump. A sunny position will always be warmer and will provide less defrosting and greater overall efficiency (and a lower running cost) than a cooler position.

Leave it on - or turn it off?

A lot depends on your lifestyle choices. Do you require a consistent heating or cooling level, 24 hours a day? Do you want a comfort level primarily during the day or overnight?

The highest electricity use in a heat pump occurs in the start-up and initial heating period - reduce the number of start-up periods per day and you will save energy and cost.

Some people make the mistake of turning their heat pumps on and off several times a day - this is not economical. If you are going out for only 1 or 2 hours - turn your heat pump down to say 16°C and then bring it back up to the normal temperature you like when you get home - it will use much less energy this way.

What about cleaning my heatpump?

Don't get ripped off! In southern NZ conditions, annual cleaning should not be necessary for most heat pumps. When it does need to be done it should take more than about half an hour. Here's what to look for...

• Keep the indoor unit filters clean - check at least once a month and vacuum from the front side only. If dirt is sticking, wash them lightly in soapy water and stand to dry before reinstalling.
• Check to see if dirt is building up between the fins of the indoor unit radiator - this may be worse when the unit is near to a kitchen. If this is happening a proper clean should be done by a qualified technician.
• Check the outdoor unit radiator fins (on the back). Look for dirt build up between the fins or moss and algae growth which will hamper air flow. This should be cleaned by a qualified technician so that damage to the fins is avoided.
• Everything else on your unit is sealed. Gas levels can only be properly checked by extracting any existing gas and reloading the system - be wary of someone who claims that they check your gas levels as part of the cleaning process.

Quality Heat Pumps from Warm and Cool

We choose to stock what we believe to be the best in modern heat pumps.

Why the different brands?

There are heat pumps and there are heat pumps... The Japanese brands simply offer the best quality, performance and value for money in heat pumps (Carrier is associated with Toshiba).

Heat pumps are constantly under development and the various companies bring new advances to the market at different times and to different segments of the market. By promoting several key brands, Warm and Cool can find the best heat pump at the time for your situation. They all look a little different and that's sometimes an important issue depending on who's paying the bill...

• Panasonic - high quality, market leading performance and great value for money. Go to www.panasonic.co.nz

• Mitsubishi - generally slightly quieter, strong cold performance (including Hypercore® on some models) - market leaders in larger sizes. Go to www.bdt.co.nz

• Toshiba - inventors of the inverter and technology leaders, excellent performance in cold conditions - excellent low-wall models. Go to www.ahi-toshiba.com

• Carrier - simplistic but still good quality, excellent value for money - great for rental properties or secondary uses. Go to www.ahi-carrier.co.nz

Look for the ENERGY STAR - the global mark of energy efficiency. Heat pumps displaying the ENERGY STAR mark reach the highest standards for operating efficiency without compromising on quality and performance.

5 year warranties - competitive quotes - full back-up service

Standard Split Systems

This is the most common installation type. There are two components to the system - the outdoor compressor unit and an indoor unit - high wall mounted or low wall mounted.

High-Wall Units

• Cheaper to buy than the equivalent low-wall models
• More obvious when installed
• May cause drafts if not sited effectively
• Can result in a cool air layer at floor level

Low-Wall Units

• More expensive than the high-wall equivalent
• More under-stated when installed
• Less likely to create uncomfortable drafts
• Can distribute air across the floor - less risk of cold feet and generally better overall air distribution.

Multi-split Systems

The operation of several indoor head units from a single outdoor unit.

This allows proper heating of individual areas within a home though it will not normally stack up cost-wise until there are at least 3 indoor units.

Limitations - when all of the units on the system are operating, the heat output from each unit is compromised and the original heat rating of the units will be reduced. Calculation of the heat loadings and specification of the correct units must be done by a qualified assessor.

All of the indoor units must operate in the same mode at the same time.

Ducted Heat Pump Systems

This type of system allows you to centrally heat your home for around half the price of an in-floor heating system.

Larger outdoor heat pumps (up to 16 kilowatts) can be installed to provide efficient heating via a ducting and vent system just like a ventilation system.

Air and heat delivery can be balanced by adjustable room vents or with automatic in-line dampers - and the system can provide cooling in summer as well!

This may be a better option than a multi-split system if you are serious about providing a level of central heating to your home.